Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell cycle analyses of activated T lymphocytes from elderly humans generally show that the proportion of noncycling cells increases with age. T cells that are not definitively blocked in G0 usually strain to traverse the G1 phase and may still be arrested at the G1/S boundary. The molecular mechanisms underlying these cell cycle arrests are unknown. Because G0/G1 and G1/S transitions are regulated in part by cyclin-dependent kinase Cdk6, we investigated the possibility that a loss of activity of this kinase is implicated in the age-related dysfunction of the cell cycle in its initial phases. G0/G1 and G1/S blocks were first confirmed by [(3)H]uridine and [(3)H]thymidine incorporation studies in anti-CD3 activated T lymphocytes derived from elderly donors. In the same cell preparations, in vitro phosphorylation of recombinant truncated Rb protein by immunoprecipitated Cdk6 was significantly decreased. The reduced Cdk6 activity was not attributable to a low level of the protein since a 24-h activation resulted in a comparable expression of the kinase in T cells from young and old individuals. However, at least two other mechanisms might be incriminated in the loss of Cdk6 activity: (1) a poor induction of the associated cyclin D2 upon anti-CD3 stimulation and (2) a delayed downregulation of the Cdk inhibitor p27 following cell activation. The low Cdk6 activity observed in T lymphocytes from the elderly was associated with a defective phosphorylation of the endogenous Rb protein and an increased sequestration of the E(2)F-1 transcription factor, possibly resulting in early cell cycle arrest.
 ...
PMID:Failure of T lymphocytes from elderly humans to enter the cell cycle is associated with low Cdk6 activity and impaired phosphorylation of Rb protein. 1055 95

Infection with either Streptococcus sanguis or Streptococcus pneumoniae type 25 causes acute pneumonitis in rats. Pneumonia caused by S. sanguis resolves over the course of 8 d, whereas pneumonia caused by S. pneumoniae type 25 progresses to fibrosis. To examine the role of apoptosis in these models, we performed assays with the terminal deoxynucleotidyltransferase-uridine nucleotide end-labeling technique on tissue sections from rat lungs at various times, and quantified the results with image analysis. Apoptosis was a feature of both the acute and resolving stages of pneumonia. The pattern and extent of apoptosis were similar in both models during the acute stage, and the number of apoptotic nuclei increased in both models through 4 d after infection. Although there were differences in the cellular pattern of apoptosis after 2 d and 4 d of infection, the extent of apoptosis was the same in both models. After 8 d, major differences were observed. In the resolving model, apoptosis was limited primarily to an abscess in the base of the lung. In the nonresolving model, apoptosis was persistent. We also found that cyclin-dependent kinase-5 expression is upregulated during apoptosis induced by bacterial infection. These data indicate that the location and timing of apoptosis may determine whether pneumonia resolves or progresses to fibrosis.
 ...
PMID:Differential patterns of apoptosis in resolving and nonresolving bacterial pneumonia. 1085 86

Expression of the Na(+)-coupled glucose cotransporter SGLT1 is regulated post-transcriptionally at the level of mRNA stability. We have previously demonstrated that cAMP-dependent stabilization of the SGLT1 message was correlated with the protein phosphorylation-dependent binding of cytoplasmic proteins to a uridine-rich sequence (URE) in the 3'-untranslated region (UTR). In the present study, the regulatory role of the URE was demonstrated by inserting it into the 3'-UTR of a beta-globin reporter minigene under the control of the tetracycline-regulated promoter. The resultant chimeric globin/SGLT1 mRNA expressed after transfection into LLC-PK1 cells exhibited a decreased half-life compared with the beta-globin control, indicating that the URE serves a destabilizing function. Activation of protein kinase A stabilized the chimeric message but not the beta-globin control, indicating the presence of a regulatory stabilizing sequence within the URE. A 38-kDa nucleocytoplasmic protein was identified that recognized a 12-nucleotide binding site within the URE. A mutation in this binding site that prevented protein binding assayed in vitro by UV cross-linking also prevented protein kinase A-dependent stabilization of the chimeric message assayed in vivo. These findings identify the interaction between a 38-kDa nucleocytoplasmic protein and a regulatory uridine-rich sequence in the 3'-UTR as critical for cAMP-mediated SGLT1 message stabilization.
 ...
PMID:Cyclic nucleotide regulation of Na+/glucose cotransporter (SGLT1) mRNA stability. Interaction of a nucleocytoplasmic protein with a regulatory domain in the 3'-untranslated region critical for stabilization. 1095 Sep 55

Leflunomide is a pyrimidine biosynthesis inhibitor that has recently been approved for treatment of rheumatoid arthritis. However, the mechanism of leflunomide's antiarthritis activity and is not fully understood. The critical role that TNF plays in rheumatoid arthritis led us to postulate that leflunomide blocks TNF signaling. Previously, we have demonstrated that leflunomide inhibits TNF-induced NF-kappaB activation by suppressing I-kappaBalpha (inhibitory subunit of NF-kappaB) degradation. We in this study show that leflunomide also blocks NF-kappaB reporter gene expression induced by TNFR1, TNFR-associated factor 2, and NF-kappaB-inducing kinase (NIK), but not that activated by the p65 subunit of NF-kappaB, suggesting that leflunomide acts downstream of NIK. Leflunomide suppressed TNF-induced phosphorylation of I-kappaBalpha, as well as activation of I-kappaBalpha kinase-beta located downstream to NIK. Leflunomide also inhibited TNF-induced activation of AP-1 and the c-Jun N-terminal protein kinase activation. TNF-mediated cytotoxicity and caspase-induced poly(ADP-ribose) polymerase cleavage were also completely abrogated by treatment of Jurkat T cells with leflunomide. Leflunomide suppressed TNF-induced reactive oxygen intermediate generation and lipid peroxidation, which may explain most of its effects on TNF signaling. The suppressive effects of leflunomide on TNF signaling were completely reversible by uridine, indicating a critical role for pyrimidine biosynthesis in TNF-mediated cellular responses. Overall, our results suggest that suppression of TNF signaling is one of the possible mechanisms for inhibitory activity of leflunomide against rheumatoid arthritis.
 ...
PMID:Leflunomide suppresses TNF-induced cellular responses: effects on NF-kappa B, activator protein-1, c-Jun N-terminal protein kinase, and apoptosis. 1106 59

Extracellular ATP suppressed the growth of HL-60 leukemia cells and induced their differentiation as revealed by N-formyl-methionyl-leucyl-phenylalanine-induced beta-glucuronidase release. ATP degraded to ADP, AMP, and adenosine, and the effect of ATP on cell growth was mimicked by these metabolites added to the cultures. The stable analog alpha,beta-methylene ATP, however, had only a weak inhibitory effect on cell growth. Adenine nucleotide-induced growth suppression was reversed by uridine, suggesting the involvement of intracellular pyrimidine starvation secondary to adenosine accumulation. Consistent with this, ATP induced intracellular starvation of pyrimidine nucleotides, and this effect was also prevented by pretreatment of cells with uridine. The order of effectiveness of ATP-induced differentiation of HL-60 cells, unlike that for growth suppression, was ATP > ADP > AMP, and adenosine had no effect. Furthermore, uridine had no effect and the stable analog, alpha,beta-methylene ATP also induced HL-60 cell differentiation, suggesting that differentiation was due to ATP per se. We tested the hypothesis that ATP-induced differentiation arises from activation of adenylyl cyclase by the novel P2Y(11) receptor using the cell-permeable inhibitor of protein kinase A, Rp-CPT-cAMPS (8-(4-chlorophenylthio)adenosine-3',5'-cyclic monophosphorothioate, Rp isomer). Rp-CPT-cAMPS (1-100 microM) prevented ATP-induced differentiation of HL-60 cells as assessed by fMLP-induced beta-glucuronidase release. However, Rp-CPT-cAMPS did not prevent ATP-induced growth suppression. Taken together, the data indicate that extracellular ATP suppresses HL-60 growth and induces their differentiation by distinct mechanisms. Growth suppression arises from adenosine generation and consequent pyrimidine starvation. Differentiation arises, at least in part, from a distinct mechanism involving the activation of cell surface P2 receptors coupled to cAMP generation and activation of protein kinase A.
 ...
PMID:Extracellular ATP-dependent suppression of proliferation and induction of differentiation of human HL-60 leukemia cells by distinct mechanisms. 1107 40

Mammalian cells express at least two subtypes of equilibrative nucleoside transporters, i.e. ENT1 and ENT2, which can be distinguished functionally by their sensitivity and resistance respectively to inhibition by nitrobenzylthioinosine. The ENT1 transporters exhibit distinctive species differences in their sensitivities to inhibition by dipyridamole, dilazep and draflazine (human>mouse>rat). A comparison of the ENT1 structures in the three species would facilitate the identification of the regions involved in the actions of these cardioprotective agents. We now report the molecular cloning and functional expression of the murine (m)ENT1 and mENT2 transporters. mENT1 and mENT2 encode proteins containing 458 and 456 residues respectively, with a predicted 11-transmembrane-domain topology. mENT1 has 88% and 78% amino acid identity with rat ENT1 and human ENT1 respectively; mENT2 is more highly conserved, with 94% and 88% identity with rat ENT2 and human ENT2 respectively. We have also isolated two additional distinct cDNAs that encode proteins similar to mENT1; these probably represent distinct mENT1 isoforms or alternative splicing products. One cDNA encodes a protein with two additional amino acids (designated mENT1b) that adds a potential protein kinase CK2 phosphorylation site in the central intracellular loop of the transporter, and is similar, in this regard, to the human and rat ENT1 orthologues. The other cDNA has a 5'-untranslated region sequence that is distinct from that of full-length mENT1. Microinjection of mENT1, mENT1b or mENT2 cRNA into Xenopus oocytes resulted in enhanced uptake of [(3)H]uridine by the oocytes relative to that seen in water-injected controls. mENT1-mediated, but not mENT2-mediated, [(3)H]uridine uptake was inhibited by nitrobenzylthioinosine and dilazep. Dipyridamole inhibited both mENT1 and mENT2, but was significantly more effective against mENT1. Adenosine inhibited both systems with a similar potency, as did a range of other purine and pyrimidine nucleosides. These results are compatible with the known characteristics of the native mENT1 and mENT2 transporters.
 ...
PMID:Molecular cloning and functional characterization of inhibitor-sensitive (mENT1) and inhibitor-resistant (mENT2) equilibrative nucleoside transporters from mouse brain. 1108 29

Adenosine 5'-triphosphate (ATP) stimulates airway epithelial Cl(-) secretion in a complicated manner. We examined the difference between ATP- and uridine 5'-triphosphate (UTP)-induced responses of short-circuit current (Isc) in bovine tracheal epithelium treated with amiloride. Each nucleotide caused an increase in Isc composed of the first and second peaks, where the second peak induced by ATP was higher compared with UTP. The ATP-induced second peak was inhibited by the protein kinase (PK) A inhibitor H89, saturation of P1 receptor with adenosine, and the P1 receptor antagonist 8-p-sulfophenyltheophylline, but not by the Ca(2+) chelator ethyleneglycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid plus the endoplasmic reticulum Ca(2+)-pump inhibitor thapsigargin, the adenosine breakdown enzyme adenosine deaminase, the ectonucleotidase inhibitor alpha,beta-methyleneadenosine 5'-diphosphate, or saturation of P2Y2 receptor with UTP. Thus, the response is associated with PKA-dependent pathway via P1-like receptor but not with Ca(2+)-dependent pathway via P2Y2 receptor, and ATP degradation products do not contribute to this response. Further, stimulation of cells with ATP increased PKA activity. In addition, pretreatment with glybenclamide, an inhibitor of cystic fibrosis transmembrane conductance regulator, reduced the second peak of Isc induced by ATP but was without effect on that induced by UTP. Therefore, ATP stimulates glybenclamide-sensitive Cl(-) secretion, and this action is partly mediated by PKA-dependent pathway via P1-like receptor.
 ...
PMID:Differential regulations between adenosine triphosphate (ATP)- and uridine triphosphate-induced Cl(-) secretion in bovine tracheal epithelium. Direct stimulation of P1-like receptor by ATP. 1158 16

The effects of extracellular nucleotide triphosphates on the stimulation of mucin production by airway epithelial cells were examined. The order of potency in stimulating mucin secretion in primary cultures of human tracheobronchial epithelial cells is: uridine 5'-triphosphate (UTP) approximately equal to adenosine 5'-triphosphate (ATP) approximately equal to ATP-gamma-S > uridine 5'-diphosphate approximately equal to adenosine 5'-diphosphate > alpha,beta-methylene ATP >> adenosine. However, only UTP can increase mucin gene (MUC5AC, MUC5B) expression; ATP and other analogues have no stimulatory effect. The stimulation of MUC5AC and MUC5B expression by UTP is time- and dose-dependent. A similar effect on the elevation of mucous cell population in mouse airway epithelium can be demonstrated in vivo by an intratracheal instillation of UTP-saline solution. The stimulatory effect of UTP or ATP on mucin secretion was inhibited by pertussis toxin, U73122, and Calphostin C, but not by PD98059, suggesting a G-protein/ phospholipase (PL) C/protein kinase (PK) C-dependent and mitogen-activated protein kinase (MAPK)-independent signaling pathway. However, the stimulatory effect of UTP on mucin gene expression was sensitive to pertussis toxin and PD98059, but not to Calphostin C and U73122, suggesting a G-protein/MAPK-dependent and PLC/PKC-independent signaling pathway. These findings are the first demonstration that UTP, a pyrimidine nucleotide triphosphate, can enhance both mucin secretion and mucin gene expression through different signaling pathways.
 ...
PMID:Differential regulation of airway mucin gene expression and mucin secretion by extracellular nucleotide triphosphates. 1169 42

1. Using a Ca(2+) imaging system and fura-2 AM (5 microM) we showed that exposure of polarised monolayers of human bronchial epithelial cells (16HBE14o- cell line) to aldosterone produced a fast intracellular [Ca(2+)] ([Ca(2+)](i)) decrease, in 70 % of cells. Exposure to aldosterone (1 nM) reduced the [Ca(2+)](i) by 39 +/- 9 nM (n = 282, P < 0.0001) within 10 min, from a basal [Ca(2+)](i) of 131 +/- 19 nM (n = 282). 2. The effect of aldosterone on [Ca(2+)](i) was not affected by inhibitors of the classical genomic pathway, cycloheximide (1 microM) or spironolactone (10 microM). The aldosterone-induced [Ca(2+)](i) decrease was inhibited by thapsigargin (1 microM), pertussis toxin (24 h at 200 ng ml(-1)), the adenylate cyclase inhibitors 2',3'-dideoxyadenosine (200 microM) and MDL-12,330A hydrochloride (500 microM), and the protein kinase A inhibitor R(P)-adenosine 3',5'-cyclic monophosphorothioate (200 microM). In addition, treatment of 16HBE14o- monolayers with aldosterone (1 nM) inhibited by approximately 30 % the large and transient [Ca(2+)](i) increase induced by apical exposure to uridine triphosphate (UTP, 0.1 mM), a known secretagogue in airway epithelia. 3. Our results demonstrate for the first time that in human bronchial epithelial cells, aldosterone decreases [Ca(2+)](i) levels via a non-genomic mechanism. The hormone-induced changes to [Ca(2+)](i) involve stimulation of thapsigargin-sensitive Ca(2+)-ATPase, via G-protein-, adenylate cyclase- and protein kinase A-coupled signalling pathways.
 ...
PMID:Rapid and non-genomic reduction of intracellular [Ca(2+)] induced by aldosterone in human bronchial epithelium. 1171 79

Mitogenic effects of the extracellular nucleotides ATP and UTP are mediated by P2Y(1), P2Y(2), and P2Y(4) receptors. However, it has not been possible to examine the highly expressed UDP-sensitive P2Y(6) receptor because of the lack of stable, selective agonists. In rat aorta smooth muscle cells (vascular smooth muscle cells; VSMC), UDP and UTP stimulated (3)H-labeled thymidine incorporation with similar pEC(50) values (5.96 and 5.69). Addition of hexokinase did not reduce the mitogenic effect of UDP. In cells transfected with P2Y receptors the stable pyrimidine agonist uridine 5'-O-(2-thiodiphosphate) (UDPbetaS) was specific for P2Y(6) with no effect on P2Y(1), P2Y(2), or P2Y(4) receptors. UDPbetaS stimulated [(3)H]thymidine and [(3)H]leucine incorporation and increased cell number in VSMC. Flow cytometry demonstrated that UDP stimulated cell cycle progression to both the S and G(2) phases. The intracellular signal pathways were dependent on phospholipase C, possibly protein kinase C-delta, and a tyrosine kinase pathway but independent of G(i) proteins, eicosanoids, and protein kinase A. The half-life of P2Y(6) receptor mRNA was <1 h by competitive RT-PCR. The mitogen-activated protein kinase kinase inhibitor PD-098059 significantly suppressed, whereas ATP and interleukin-1beta upregulated, expression of P2Y(6) receptor mRNA. The results demonstrate that UDP stimulates mitogenesis through activation of P2Y(6) receptors and that the receptor is regulated by factors important in the development of vascular disease.
 ...
PMID:UDP acts as a growth factor for vascular smooth muscle cells by activation of P2Y(6) receptors. 1178 30


<< Previous 1 2 3 4 5 6 7 8 9 Next >>